Imbalances

When cells are incubated in hypertonic medium, initiation of new polypeptide chains stops and polysomes are quickly disaggregated. The synthesis of viral proteins in cells infected with poliovirus, however, is appreciably less sensitive to such treatment than is host protein synthesis (Nuss et ai, 1975). 

After infection with a variety of viruses, cell membranes become more permeable (Kohn, 1979). It has been suggested that the consequent disturbance of the intracellular balance of ions may account for the interference with the synthesis of cellular macromolecules (Carrasco and Smith, 1976 Carrasco, 1977 Durham, 1977). It was reported, in support of this mechanism, that the optimum concentration of monovalent ions for the translation of picornaviral mRNA in vitro was higher than that required for translation of cellular mRNA, and that the shut-off of host protein synthesis by EMC virus 

Other experiments with herpesviruses have lent only limited support to the theory that ionic imbalance causes selective shut-off of cellular protein synthesis after infection. A differential sensitivity to hypertonic medium has been reported in cells infected with human or murine cytomegaloviruses which cause only a very slow decline late in infection (Gupta and Rapp, 1978 Chantler, 1978), but in HSV-2-infected cells (Fenwick and Walker, 1978) and PRV-infected cells (Stevely and McGrath, 1978) viral protein synthesis was as susceptible as protein synthesis in uninfected cells to increased concentrations of NaCl. No differences have been found between the concentrations of ions needed for optimal translation in vitro of viral (HSV-1 or PRV) and cellular mRNAs, respectively (Inglis and Newton, 1981 McGrath and Stevely, 1980). Attempts to prevent the early shut-off of protein synthesis by HSV-2 by reducing the Na or Ca concentration in the medium were not successful (Fenwick and Walker, 1978), but these experiments were done at times which probably preceded the permeability changes described by Benedetto et al. (1980). 

There is, thus, at present, no reason to suppose that early shutoff by HSV, involving displacement of ribosomes from mRNA, is caused by changes in intracellular ion concentrations. Delayed shutoff by those viruses that do not cause early virion-associated shutoff may possibly be related to a late increase in permeability of the 

Delayed shut-off of protein synthesis appears to involve the degradation of cellular mRNA and is conditional upon the synthesis of viral RNA and protein. Which viral protein is concerned is not known all three classes, a, p, and y, have been suspected of being involved. 

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Analogous effects are caused by the inappropriate use of utilities. Utilities are appropriate if they are necessary to satisfy the enthalpy imbalance in that part of the process. Above the pinch in Fig. 6.7a, steam is needed to satisfy the enthalpy imbalance. Figure 6.86 illustrates what happens if inappropriate use of utilities is made and some cooling water is used to cool hot streams above the pinch, say, XP. To satisfy the enthalpy imbalance above the pinch, an import of (Q mjj,+XP) is needed from steam. Overall, (Qcmin+AP) of cooling water is used. ... 

An alternative inappropriate use of utilities involves heating of some of the cold streams below the pinch by steam. Below the pinch, cooling water is needed to satisfy the enthalpy imbalance. Figure... 

The process requires (Qup + Qlp) to satisfy its enthalpy imbalance above the pinch. If there were no losses from the boiler, then fuel W would be converted to shaftwork W at 100 percent efficiency. However, the boiler losses Qloss reduce this to below 100 percent conversion. In practice, in addition to the boiler losses, there also can be significant losses from the steam distribution system. Figure 6.336 shows how the grand composite curve can be used to size steam turbine cycles. ... 

By comparison, Fig. 13.36 shows an exothermic reactor integrated below the pinch. Although heat is being recovered, it is being recovered into part of the process which is a heat source. The hot utility requirement cannot be reduced because the process above the pinch needs at least Q//m-,n to satisfy its enthalpy imbalance. 

Hydrate formation is possible only at temperatures less than 35°C when the pressure is less than 100 bar. Hydrates are a nuisance they are capable of plugging (partially or totally) equipment in transport systems such as pipelines, filters, and valves they can accumulate in heat exchangers and reduce heat transfer as well as increase pressure drop. Finally, if deposited in rotating machinery, they can lead to rotor imbalance generating vibration and causing failure of the machine. 

Surface tension arises at a fluid to fluid interface as a result of the unequal attraction between molecules of the same fluid and the adjacent fluid. For example, the molecules of water in a water droplet surrounded by air have a larger attraction to each other than to the adjacent air molecules. The imbalance of forces creates an inward pull which causes the droplet to become spherical, as the droplet minimises its surface area. A surface tension exists at the interface of the water and air, and a pressure differential exists between the water phase and the air. The pressure on the water side is greater due to the net inward forces... 

Interesting pattern formations also occur in surfactants spreading on water due to a hydrodynamic instability [52]. The spreading velocity from a crystal may vary with direction, depending on the contour and crystal facet. There may be sufficient imbalance to cause the solid particle to move around rapidly, as does camphor when placed on a clean water surface. The many such effects have been reviewed by Stemling and Scriven [53]. 

With three bubbles, the septa must meet at 120° if the system is to be mechanically stable. A fourth bubble could now be added as shown in Fig. XIV-14, but this would not be stable. The slightest imbalance or disturbance would suffice to move the septa around until an arrangement such as in Fig. XIV-14h resulted. Thus a two-dimensional foam consists of a more or less uniform hexagonal type of network. 

Outside the OHP, there may still be an electric field and hence an imbalance of anions and cations extending in the fomi of a diffuse layer into the solution. 

Equation (A3.3.73) is referred to as the Gibbs-Thomson boundary condition, equation (A3.3.74) detemiines p on the interfaces in temis of the curvature, and between the interfaces p satisfies Laplace s equation, equation (A3.3.71). Now, since ] = -Vp, an mterface moves due to the imbalance between the current flowing into and out of it. The interface velocity is therefore given by... 

Any charge imbalance in a plasma (i.e. any local deviation from charge neutrality) results in a motion of tire electrons tliat, in turn, leads to oscillations of tire electrons witli tire electron plasma frequency C0p (Langmuir frequency)... 

METHOD 3 The authors next stepped back and considered the cosmic imbalance caused by that 6-day reaction time. The next recipe was what they came up with. 

We now turn to two of the problems we have sidestepped until now. In this section we consider the polymerization of reactants in which a stoichiometric imbalance exists in the numbers of reactive groups A and B. In the next section we shall consider the effect of monomers with a functionality greater than 2. 

We define the problem by assuming the polymerization involves AA and BB monomers and that the B groups are present in excess. We define and to be the numbers of A and B functional groups, respectively. The number of either of these quantities in the initial reaction mixture is indicated by a superscript 0 the numbers at various stages of reaction have no superscript. The stoichiometric imbalance is defined by the ratio r, where... 

The parameter r continues to measure the ratio of the number of A and B groups the factor 2 enters since the monofunctional reagent has the same effect on the degree of polymerization as a difunctional molecule with two B groups and, hence, is doubly effective compared to the latter. With this modification taken into account, Eq. (5.40) enables us to quantitatively evaluate the effect of stoichiometric imbalance or monofunctional reagents, whether these are intentionally introduced to regulate or whether they arise from impurities or side reactions. 

For any value of p, n is greater for larger values of r stoichiometric imbalance lowers the average chain length of the preparation. 

Suppose the total number of carboxyl groups in the original mixture is 2 mol, of which 1.0% is present as acetic acid to render the resulting polymer inert to subsequent esterification. What value of p would be required to produce the desired polymer in this case, assuming no other stoichiometric imbalance ... 

Cobalt, copper, molybdenum, iodine, iron, manganese, nickel, selenium, and zinc are sometimes provided to mminants. Mineral deficiency or toxicity in sheep, especially copper and selenium, is a common example of dietary mineral imbalance (21). Other elements may be required for optimal mminant performance (22). ExceUent reviews of trace elements are available (5,22). 

Diagnosis and alleviation of the cause, if possible, is of primary importance. Often, however, this is not possible and therapy is used to alleviate the inconvenience and pain of diarrhea. These compounds usually only mask the underlying factors producing the problem. Diarrhea may cause significant dehydration and loss of electrolytes and is a particularly serious problem in infants. Antidiarrheals do not usually prevent the loss of fluids and electrolytes into the large bowel and, although these may prevent frequent defecation, often the serious imbalance of body electrolytes and fluids is not significantly affected. 

MPD-1 fibers may be obtained by the polymeriza tion of isophthaloyl chloride and y -phenylenediamine in dimethyl acetamide with 5% lithium chloride. The reactants must be very carefully dried since the presence of water would upset the stoichiometry and lead to low molecular weight products. Temperatures in the range of 0 to —40° C are desirable to avoid such side reactions as transamidation by the amide solvent and acylation of y -phenylenediamine by the amide solvent. Both reactions would lead to an imbalance in the stoichiometry and result in forming low molecular weight polymer. Fibers are dry spun direcdy from solution. 

Perhaps the most striking feature shown in Table 4 is the large imbalance between regional production and consumption in the Middle East as compared to OECD Europe. In 1992, the Middle East produced five times more cmde petroleum than it consumed, and OECD Europe consumed about three times more cmde petroleum than it produced that is, in 1992, the Middle East exported about 81% of its production of cmde petroleum, whereas OECD Europe imported about 66% of the cmde petroleum that it consumed. In the Asia/AustraUa region, 2419 x 10 m /d (15.2 x 10 bbl/d), or 23.3% of the world s total, was consumed in 1992. In the United States, production of cmde petroleum peaked in 1971 and has declined since then so that only 54.5% of the U.S. cmde petroleum consumed in 1992 was produced domestically. In Latin America, production of cmde petroleum stood at about 150% of consumption, whereas in 1978, production and consumption were about equal. 

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